Vestar has developed a liposomal drug delivery system comprised of (MTX) encapsulated in the internal aqueous space of small unilamellar vesicles and human recombinant IL-2 covalently coupled to the exterior surface. The complex is called SUV-MTX-IL-2 (SMI). It is designed to target to the high affinity IL-2 receptor of aberrantly activated T cells that participate in graft rejection and several autoimmune disorders. In vitro studies at Vestar has shown that this drug delivery system primes activated human PBL to proliferate due to the IL-2 present and then inhibits further growth of proliferating T cells due to the presence of (MTX) transported into the cytoplasm. The goal of this study will be to show that SMI inhibits the growth of antigen-specific T cells in oxazolanone-induced delayed hypersensitivity produced in rats. SMI is prepared with a novel technology designed to protect the IL-2 receptor binding domain on IL-2, and the methodologies used can be scaled up to prepare sterile SMI which exhibits adequate stability during storage. The commercial objective is to develop a liposomal product which targets an antiproliferative drug to unwanted cells of the immune system while minimizing the toxicity that is currently associated with the free drug.